1. Field of the Invention
The disclosure is related to a molten iron-assisted method for producing aluminum nitride and a device thereof, and more particularly to a method for producing aluminum nitride and a device thereof having a rapid producing rate and simplified process.
2. Description of Related Art
Aluminum nitride has great thermal conductivity (theoretical value: 320 W/mK), great electrical insulation, a small coefficient thermal expansion (4.3 ppm/K, which is closed to silicon), great thermal shock resistance and great corrosion resistance. Thus, aluminum nitride has become an important material in the industry in recent years. Aluminum nitride has great potentials in a variety of applications of high technology industry, including electrical substrates, integrated circuit packaging materials, heat dissipating element in electric elements, composite materials with high thermal conductivity, containers for containing and treating melt salts or metals and so forth.
Currently, methods for producing aluminum nitride in the industry, such as carbon reductive nitridation of aluminum oxide powder (Tokuyama, Japan) and direct nitridation of aluminum powder (ART, US; H. C. Starck, German), have the following disadvantages: consume much power, slow producing rate, complicated processes, and high cost, rendering expensive the application aluminum nitride. Since aluminum nitride is expensive, the scale of market cannot grow significantly as what experts expected. Instead, it only grows by a small extent stably; however, people in the industry hold the view that if the price of aluminum nitride can be greatly reduced (for example, by 30%), the demand of aluminum nitride will significantly increase, and the market will grow significantly as expected.
Since the cost of producing aluminum nitride currently is high, the only way to greatly decrease the price of aluminum nitride is to develop a process with high quality and low cost; currently, main methods for producing aluminum nitride are carbon reductive nitridation of aluminum oxide powder and direct nitridation of aluminum, wherein the method of direct nitridation of aluminum has the problem of fusion of aluminum, aluminum with high purity cannot be obtain in one reaction, and numerous processes of grinding, re-reacting as well as operating under a high temperature for a long time are needed. Together, such methods could be extensively power-consuming.
In addition, aluminum with high purity can be obtained by the method of carbon reductive nitridation of aluminum oxide powder. However, the obtained product has too much amount of carbon, so that carbon has to be removed by oxidation under an atmosphere having oxygen, which would cause the increase of the amount of oxygen in the product. In addition, the method also needs to be performed under a high temperature for a long time, further contributing to extra power consumption.
Accordingly, there are no methods and devices having a fast producing rate and simple processes for producing aluminum nitride. Thus, it is important to develop a method for producing aluminum nitride which can increase the producing rate and yield, and can save power and cost so as to solve the problem that producing aluminum nitride is expensive.